Fiber optic arc lamp system

ABSTRACT

The invention pertains to a fiber optic lamp system such as those employed in medical diagnostic systems using a cabinet containing a power supply having a front extendible drawer containing a 250 watt focused beam metal halide arc lamp mounted in a removable bracket which includes a sensing tab extension. The bracket sensing tab operates an electrical interlock switch when the proper lamp is properly installed. The interlock switch controls power to the system whose circuit includes pin and floating sleeve electrical connectors which automatically directly completes the circuit to the arc lamp upon the drawer being closed. The amount of light transferred to the fiber optic cable is optimized by offsetting the axis of focused light with respect to the optic cable axis at the cable interface.

This is a division of application Ser. No. 07/753,302 filed Aug. 30,1991.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present application relates to medical diagnostic apparatus forintroducing a high intensity light beam into a fiber optic cable.

2. Description of Related Art

Fiber optic cable illumination apparatus is used for medical diagnosticpurposes wherein a focused lamp supplies light to an optic cableinterface. Such devices operate most efficiently when the proper lamp isproperly focused. However, present units permit improper lamps to besubstituted during lamp replacement. Additionally, present illuminationapparatus requires manual electrical connections be made during lampreplacement necessitating a higher degree of skill by the operator thanis desirable.

Fiber optic systems are known to have inefficient light introductioninterfaces due to the spaces between the fibers which contribute littleto the interface when the light source impinges directly upon them.Also, due to the contour of the light beam impinging on the flat, planarfiber ends, an effect known as Newtonian ring interference causes ringsof color light to appear at the cable output which reduces theillumination quality of the cable bundle. Known illumination apparatushave not effectively overcome this phenomenon.

OBJECTS OF THE INVENTION

In view of the foregoing deficiencies of medical illumination apparatus,it is an object of the invention to provide a more powerful andefficient high intensity light source for the transmission of light bymeans of fiber-optical cables.

A further object of the invention is to provide an essentially purewhite light for fiber-optical cable transmission and to provide a moreefficient application of light to a fiber optical cable interface.

Yet another object of the invention is to provide a method of preventingelectrical shock to personnel servicing the lamp assembly when the lampsupporting drawer is extended and to insure proper electrical connectionto the lamp assembly before energizing the lamp electrical connections.

A further object of the invention is to provide a lamp replacementsystem for medical diagnostic apparatus which substantially eliminatesthe likelihood of improper lamps being installed through the use of anelectrical interlock which completes the circuit to the lamp only uponthe proper lamp being properly positioned with respect to the opticalcable interface.

SUMMARY OF THE INVENTION

These objects are accomplished, in part, through the novel use of aninternally focused metal halide arc lamp as a light source for medicaldiagnostic illumination apparatus. The halide arc lamp provides asignificantly greater light intensity than a comparable wattageincandescent lamp. Additionally, the halide arc lamp provides light of amulti-color spectra through a differential reflector focusingconfiguration such that the light quality at the focal beam is adjustedto achieve an exceptionally intense white light which is superior forpurpose of illumination in the medical field wherein the light source isdistributed through fiber optic cables.

It has been found that among the problems attendant with fiber opticlight transmission technology is the inefficient transmission of lightinto the cables through the fiber optic cable interface and the presenceof Newtonian interference rings at the cable output. The inventionemploys a metal halide arc light having a focused output beam having anaxis, the focal point of the beam is directed to impact at the fiberoptic cable interface and the beam axis is at an angle of about 10°relative to the cable interface axis. This angle increases the amount oflight carried through the cable through enhancement of the acceptanceangle of the converging beam to the end of the cable bundle while alsominimizing the Newtonian ring interference at the light output.

In order to avoid potential shock hazard, the circuit to the bulb powerreceptacles located in the housing and the bulb connectors mounted on aslidable drawer supporting the lamp is interrupted when the drawer isopened to expose the lamp for replacement purposes. The electricalcircuit to the lamp is automatically restored when the drawer is closed.

Further, the apparatus includes an interlock feature located on abracket directly attached to the proper lamp and when a proper lamp andbracket are installed, an interlock tab defined on the lamp mountingbracket closes an electrical interlock switch when the bracket isproperly positioned which completes the circuit to the bulb powerreceptacles. This unique tab interlock is such that improper lampsplaced within the bracket cannot activate the unit, nor can theelectrical interlock switch be inadvertently activated through othermeans.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be clearly understood, it will now bedescribed, by way of example, with reference to the accompanyingdrawings, wherein:

FIG. 1 is a perspective view of medical diagnostic illuminationapparatus in accord with the invention having a lamp supporting drawerpartially extended from its cabinet enclosure,

FIG. 2 is an enlarged detail cut-away perspective view of the cabinetand drawer as viewed from the drawer outer side,

FIG. 3 is an enlarged plan detail cut-away view showing the lamp bracketinterlock switch assembly,

FIG. 4 is a elevational detail view, partly in cross-section, showingthe bracket interlock tab engaging the interlock switch, the insulatorcolumns being omitted for purposes of illustration,

FIG. 5 is a front elevational view of the lamp bracket, per se,

FIG. 6 is a rear elevational view of the lamp bracket partially insertedinto the lamp bracket holder per se, the insulator columns not beingillustrated,

FIG. 7 is a elevational detail side view, partially in cross-section ofthe heat sink and lamp assembly, the insulator columns and lamp bracketholder being omitted for purpose of illustration,

FIG. 8 is a detail plan view, partially in section, of the drawer faceand lamp assembly, the lamp bracket holder being omitted for purpose ofclarity,

FIG. 9 is a detail plan view of the lamp assembly lamp plugs inengagement with the floating receptacle bracket when the drawer isclosed,

FIG. 10 is an elevational detail sectional view of the connector systemshowing lamp plug engagement with the floating receptacle bracket whenthe drawer is closed, the lamp components and the lamp bracket holderbeing omitted for purpose of illustration

FIG. 11 is an elevational view of the lamp assembly and bracket, per se,the insulator columns being omitted for purpose of illustration,

FIG. 12 is an enlarged detail elevational view of the floating lampconnector, partially in section, and

FIG. 13 is an elevational view of the floating receptacle connectormember as taken along 13--13 of FIG. 10.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A medical diagnostic fiber optic light source apparatus for thesupplying of light for illumination to a fiber optic cable interfaceutilizing the invention is generally indicated at 10 of FIG. 1, and thelight source apparatus includes a cabinet housing 12 with a slidinglyinsertable drawer 14 adapted to facilitate component maintenance. Insidethe housing 12 is a standard power supply, not shown, which provideselectrical power to the drawer circuitry.

When the drawer 14 is extended from the cabinet front openingcompartment 16, the resulting exposed, energized electrical surfacespose an electrical shock hazard which is avoided in the invention byusing a separating connector system, as illustrated in FIG. 10, whichautomatically electrically disconnects an installed 250 watt focusedbeam metal halide arc lamp 18, as the drawer is withdrawn from thecabinet.

The separating connector system comprises two power connector pins 20 onstandoff insulators 22 which horizontally extend from a verticallymounted lamp bracket 24 with a bridging insulative spacing member 26between them. Electrical connection between the pins 20 and the metalhalide arc lamp 18 are made by wires 28 extending from a lamp baseconnector 30 and a second lamp terminal 31 to solder pads on the spacingmember 26 in electrical connection with the power connector pins 20.These rigidly extending pins 20 make connection with two complementaryaligned, longitudinally spaced radially floating sleeve connectors 32mounted upon and through an opposing insulated cabinet mountedreceptacle bracket 34 when the lamp bracket 24 is correctly seated inthe lamp bracket holder 36 which is fixed to the drawer 14.

The cabinet receptacle bracket 34 is fabricated of a durable insulatingmaterial such as nylon secured by screws 38 to a contiguous cabinetmounting plate 40, FIG. 2. While the preferred embodiment employsenlarged sleeve connector mounting holes 33 in the bracket 34 whichcooperate with floating sleeves connectors 32 and their associatedconnector nuts 42 which are secured in a spaced relationship to thebracket 34, it is anticipated that other locations and connector typesmay be substituted for the configuration of the preferred embodimentwithout departing from the inventive concepts. The space 44 between thebracket and the floating sleeve connectors allows the sleeve connectors32 to axially pivot thereby facilitating alignment with the pins 20which enables the drawer to be closed and the electrical connectionsmade in spite of any relatively minor pin and sleeve connectormisalignment which may exist. Electrical connection is made to thesleeve connectors 32 by means of a ring lug connector terminated wire 46which is secured between the two connector nuts 42 and to whichelectrical current is supplied by the power supply, not shown.

An interlock switch 48 prevents power supply energization unless the arclamp bracket 24 is properly in place as is sensed by the cooperation ofa lamp bracket interlock tab 50 with the interlock switch plunger 52.The lamp bracket lower edge 54 engages the lamp bracket holder bottomflange 56 when the bracket 24 is fully inserted, as illustrated in FIG.2. As seen in FIG. 6, the lamp bracket side edges 58 slidingly engagespaced lamp bracket holder guide tabs 60, homogeneously formed of thebracket holder material, thereby assuring proper lamp bracket alignmentas the bracket 24 is inserted into the guide tabs 60 for parallelmounting upon holder 36. Should improper bulb installation occur, thepower connector pins 20 will not align with and engage the cabinetfloating sleeve connectors 32 thereby preventing power from beingapplied to the lamp 18. Furthermore, the bracket interlock tab 50, anextension of the lamp bracket 24, will ensure that the floating sleeveconnectors 32 will be activated only if the lamp 18 is correctly inplace prior to closing the lamp drawer 14. The tab construction is suchthat other bulbs placed within the unit cannot activate the unit, norcan the unit be activated by another means. When the lamp bracket 24 isproperly fully seated in the lamp bracket holder 36, the interlock tab50 extends downward through a drawer interlock hole 62, FIG. 4, which ismounted on the drawer bottom surface 64 adjacent and beneath the lampbracket holder.

The interlock switch 48 is mounted to the lower surface to the drawerbottom 64 in a longitudinal orientation. The plunger 52 longitudinallyextends from the interlock switch 48 to a position beneath the drawerinterlock hole 62 and the plunger end is beveled to provide a camsurface engageable by tab 50 which axially displaces the plunger whenthe lamp bracket 24 is correctly and fully seated. The interlock switch48 interrupts the electrical power to the cabinet power supply if thearc lamp 18 is not installed or is improperly installed thereby assuringsafe operation.

The mounting alignment and location of metal halide lamps is criticalfor the proper application of highly focused light onto the associatedfiber optic bundle. By using an interlock tab 50 in conjunction with thesquare lamp bracket holder 36 and bracket holder guide tabs 60, the lampassembly is not only positioned laterally, but is also maintained in thepreferred square, vertical position by the engagement of the lampbracket top flange 70 and the bracket holder top edge 55.

The employment of an internally focused beam high intensity metallichalide arc lamp in accord with the invention provides a white light forillumination which is less prone to affect target color appearance thanone of a yellow hue, and to the inventors' knowledge, such lamps havenot been used previously with medical diagnostic apparatus. The lightoutput of a metal halide arc lamp is a consequence of the process bywhich a differential reflector focusing technique is applied to thelight of multiple color spectra such that the light quality at the focalbeam is adjusted to achieve white light. Furthermore, the lamp providessignificantly greater light intensity for a given wattage bulb than thatwhich can be attained with an incandescent lamp.

The invention anticipates that in order to use a metal halide arc lamp aspecial configuration must be employed in order to provide enhancedperformance, acceptable service life and economical construction. One ofthe critical factors associated with the very high intensity of metalhalide lamps is the characteristically great amount of lamp heatgenerated by the lamp's operation, and specifically present in the lightbeam at its focal point 72, FIGS. 7 and 8. In order to safely dissipatethe arc lamp heat and minimize thermal stresses to the systemcomponents, three techniques are used.

First, by employing a member interposed between the arc lamp 18 andbracket 24 which will allow for thermal expansion of the lamp andcomponents coming in contact with it, mechanical stresses to thecomponents can be minimized thereby increasing service life. Such amember's effectiveness in minimizing stresses can be further enhanced ifit has good insulative qualities. In the preferred invention, spacers 74are interposed between an annular circumferential ceramic halide arclamp collar 76 and the lamp bracket 24. The halide arc lamp collar 76 isinterposed adjacent to the lamp face 78 and spaced from the lamp bracket24 to minimize drawer face heating. The spacers 74 in this configurationserve several purposes: a) they remove the lamp face from the bracket;b) they provide a means of adjustment for lamps having diverse focalpoints; and c) by using spacers of diverse selected lengths, the focusedlamp beam axis and bundle interface angle can be varied to enhance thebundle interface angle of acceptance.

The support of the halide arc lamp on the bracket 24 is completed byfixing the halide lamp intermediate the collar spacers 74 and fourwashers 86 mounted on spaced standoff insulators 82. Each standoffinsulator 82 is mounted upon and extends from the lamp bracket 24alongside the lamp collar 76 and is secured with a screw 84 to securelyclamp the arc lamp 18 into place between a spacer 74 and a washer 86 ascan be appreciated by reference to FIG. 9.

Secondly, a vaned heat sink 88 is placed intermediate the lamp bracketholder 36 and the drawer face 90, which has a central aperture 92 forpassage of the lamp light beam 94 through the heat sink 88 to the fiberoptic bundle interface 80, FIG. 8. Air is constantly forced over theheat sink 88 by a fan within cabinet 12 discharging air through port 95,FIG. 1, thereby keeping drawer face 90 temperatures within an acceptablerange.

Thirdly, the drawer face heating due to arc lamp radiation is alsominimized by the orientation of the lamp beam axis at an approximately10° horizontal angle relative to the face plane and bundle central axis96, as seen in FIG. 8, which allows proper application of the light tothe fiber optic interface yet minimizes the heat applied to the forwardface of the drawer and the enclosure.

The most important benefit of angling the arc lamp to the optic bundleaxis is an increased efficiency of light transferred to the bundle fromthe beam focal point 72 at the bundle interface 80. In using metalhalide arc lamps in conjunction with fiber optic cables, it has beenfound that by directing the light to the bundle interface at an angle,rather than in alignment with the bundle axis, a more efficient transferof light results due to enhancement of the acceptance angle of theconverging beam to the end of the bundle, consequently, more light istransferred to and carried through the bundle. It has been determinedthat by deviating the lamp beam axis between 8° and 12° from the opticfiber bundle axis optimum improved results are achieved, and preferably,a 10° angle deviation is employed.

Newtonian ring interference patterns normally occur which degrade theoutput light quality from fiber optic cables. Newtonian rings are causedby light interference from the contact of the conical light wave'sspherical front when it contacts the planar fiber optic fiber interface.The invention's significant advancement to the art of angling the arclamp as previously described improves the quality of light at the bundleoutput by the minimization of Newtonian ring interference patterns.

A turret assembly 98 is located on the drawer face 90 which is rotatableand selectively aligns the fiber optic interface of one of several sizesof fiber optic cables with the aperture 92, the appropriate size ofcable may be inserted in the correspondingly sized connection sleeve102. The cables are secured by set screws 106 installed on each of theseveral turret connection sleeves 102.

It is appreciated that various modifications to the inventive conceptsmay be apparent to those skilled in the art without departing from thespirit and scope of the invention.

We claim:
 1. Fiber optic medical diagnostic light source apparatus forsupplying light to a fiber optic interface which is attached to acabinet having a power supply comprising, in combination, a drawerreceiving opening defined in the cabinet, a lamp drawer slidinglyreceived within said cabinet drawer receiving opening selectivelypositionable between open and closed positions, a drawer face defined onsaid drawer, fiber optic cable connection means defined on said drawerface having a light passage intersecting said drawer face, a lampmounted on said drawer, lamp mounting means for mounting said lamp onsaid drawer in a fixed relationship to the fiber optic cable interface,a pair of first electrical connectors defined on said drawer connectedto said lamp for supplying electricity thereto, a pair of secondelectrical connectors mounted in the cabinet connected to the powersupply, said first and second connectors engaging and disengaging atsaid drawer closed and open positions, respectively, whereby the circuitto said lamp is completely disconnected from the power supply when saiddrawer is in said open position.
 2. In fiber optic light sourceapparatus as in claim 1, at least one pair of electrical connectorscomprising parallel elongated pins and the other connector comprising apair of sleeves each having a bore, the sleeve bores being parallel andadapted to receive a pin upon the drawer being in a closed position, andsupport means for one of said pair of electrical connectors movablysupporting the associated connectors to permit self alignment which theother of said pair of connectors.